Exposures to per- and polyfluoroalkyl substances in environmentally overburdened communities


A. Hernandez

April 11, 2023

Study design/goals


Goal:

  • Assess the relationship between environmentally overburdened communities and PFAS point sources + contamination sites


Design:

  • Aggregate information about PFAS point sources and contamination sites
  • Match sites to a census tract
  • Assess socio-demographic and environmental characteristics at the census tract

Measuring/assessing environmental justice cont.


  • The Environmental Justice Index (EJI), developed by CDC and ATSDR, is a multi-dimensional index that accounts for cumulative exposures and disproportionate health outcomes

  • Compares census-tract level environmental, social, and health-based community indicators

  • Unlike EPA’s EJSCREEN and CDC’s Social Vulnerability Index, the EJI quantifies the cumulative impact of environmental burdens on health

Environmental Justice Index

Creating the Environmental Justice Index


For each module:

  1. Order/sort the census tracts on a scale from 0 to 100 for a given variable to get a ranked percentile (RP)
    • Ex: each tract’s percentile rank indicates the percentage of tracts equal to or lower than its burden for that environmental variable
  2. For each tract, sum the percentile ranks of the module (SP)
    • all variables weighted equally
  3. Order the summed percentile ranks (SP) for that module on a scale from 0 to 100 to get a ranked percentile (RP)


Once all modules have a summed percentile (SP), sum the SP to get a summed EJI (SP_EJI). Order the SP_EJI on a scale from 0 to 100 and generate a new ranked percentile (RP).

Creating the Environmental Justice Index: Example

geoid variable value module
48029980100 EPL_OZONE 0.85 EBM
48029980100 EPL_PM 0.50 EBM
48029980100 EPL_DSLPM 0.50 EBM
48029980100 EPL_TOTCR 0.59 EBM
48029980100 EPL_NPL 0.00 EBM
48029980100 EPL_TRI 0.85 EBM
48029980100 EPL_TSD 0.95 EBM
48029980100 EPL_RMP 0.00 EBM
48029980100 EPL_COAL 0.00 EBM
48029980100 EPL_LEAD 0.00 EBM
48029980100 EPL_PARK 0.49 EBM
48029980100 EPL_HOUAGE 0.73 EBM
48029980100 EPL_WLKIND 0.76 EBM
48029980100 EPL_RAIL 0.52 EBM
48029980100 EPL_ROAD 0.32 EBM
48029980100 EPL_AIRPRT 0.99 EBM
48029980100 EPL_IMPWTR 0.22 EBM
48029980100 EPL_MINRTY 0.77 SVI
48029980100 EPL_POV200 0.75 SVI
48029980100 EPL_NOHSDP 0.13 SVI
48029980100 EPL_UNEMP 0.94 SVI
48029980100 EPL_RENTER 0.45 SVI
48029980100 EPL_HOUBDN 0.92 SVI
48029980100 EPL_UNINSUR 0.86 SVI
48029980100 EPL_NOINT 0.20 SVI
48029980100 EPL_AGE65 0.06 SVI
48029980100 EPL_AGE17 0.26 SVI
48029980100 EPL_DISABL 0.02 SVI
48029980100 EPL_LIMENG 0.46 SVI
48029980100 EPL_MOBILE 0.00 SVI
48029980100 EPL_GROUPQ 0.99 SVI
module SPL
EBM 8.27
SVI 6.81

Creating the Environmental Justice Index: Example

Creating the Environmental Justice Index: Example

geoid variable value
48029980100 SPL_EBM 8.27
48029980100 RPL_EBM 0.90
48029980100 SPL_SVM 6.82
48029980100 RPL_SVM 0.50
48029980100 F_HVM 1.00
48029980100 RPL_HVM 0.20
48029980100 SPL_EJI 1.60
48029980100 RPL_EJI 0.67

PFAS sources

Characteristic N = 35,5381
Dataset
    Part 139 Airports 532 (1.5%)
    EPA Stewardship Program Participating Facilities 16 (<0.1%)
    Facilities in Industries that may be Handling PFAS 31,902 (90%)
    Federal Agency Locations with Known or Suspected PFAS Detections 694 (2.0%)
    Fire Training Sites 448 (1.3%)
    Facilities that Manufacture or Import PFAS 807 (2.3%)
    Superfund Sites with PFAS Detections 894 (2.5%)
    Known PFAS Spills/Release Incidents 245 (0.7%)
1 n (%)

PFAS burden estimation

PFAS burden estimation: Adding a buffer

PFAS burden estimation: Adding a buffer

PFAS burden estimation: Combine the buffer

PFAS burden estimation: Find the intersection with a census tracts

PFAS burden estimation: Calculate % of census tract that intersects with PFAS buffer

\[ \text{perc_area_pfas}_i = \dfrac{\sum\text{area}(\text{PFAS point source with 1 mile buffer that overlaps with census tract i})}{\text{area}(\text{census tract i})}*100\% \]

PFAS burden estimation: % of census tract that intersects with PFAS buffer

PFAS burden estimation: % of census tract that intersects with PFAS buffer

PFAS burden estimation: Percentile rank of % of census tract within 1-mile buffer of PFAS source

PFAS burden map

PFAS burden estimation: Distribution

Table 2

Characteristic All Census Tracts Number of PFAS point sources
N = 71,680 0, N = 26,359 ≥ 1, N = 45,321 p-value1
% of census tract within 1-mile of a PFAS source
    Median (IQR) 6 (0 - 64)
    Mean (SD) 31 (39)
Sum of the HVM, EBM, and SVM module percentile ranks <0.001
    Median (IQR) 1.26 (0.82 - 1.80) 1.06 (0.66 - 1.58) 1.37 (0.93 - 1.93)
    Mean (SD) 1.33 (0.65) 1.14 (0.60) 1.43 (0.64)
Sum of the EBM variable percentile ranks <0.001
    Median (IQR) 6.09 (4.98 - 7.26) 5.20 (4.32 - 6.16) 6.64 (5.59 - 7.71)
    Mean (SD) 6.15 (1.61) 5.27 (1.35) 6.65 (1.53)
Sum of the SVM variable percentile ranks <0.001
    Median (IQR) 6.84 (5.24 - 8.42) 6.56 (5.02 - 8.03) 7.02 (5.39 - 8.62)
    Mean (SD) 6.81 (2.07) 6.53 (2.02) 6.97 (2.08)
Total number of HVM tertile flags <0.001
    Median (IQR) 1.00 (0.00 - 3.00) 1.00 (0.00 - 3.00) 1.00 (0.00 - 3.00)
    Mean (SD) 1.63 (1.54) 1.67 (1.55) 1.60 (1.53)
1 Wilcoxon rank sum test

Distribution of % of census tract within 1-mile of a PFAS source by quartiles of EJI modules

the end